1. Field of the Invention
This invention relates generally to fluid displacement devices such as rotary engines and more particularly to improvements in rotary engines of the rotary piston with reciprocal cylinders type which can be utilized as a pump or motor. In the preferred embodiment its use as an air motor having high speed capabilities will be described.
2. Description of the Prior Art
U.S. Pat. No. 3,645,172 discloses a fluid pump or motor in the form of a wheel drive having an outer rotatable driven ring to which a plurality of inwardly extending pistons are secured. The pistons are received in cylinders, the inner ends of which cylinders are mounted on an inner ring and move translatory relative thereto. A pair of annular positioning rings mount all of the cylinders to the inner ring and in order for the cylinders to move relative to the inner ring, they must move relative to the positioning rings. This engagement between the positioning rings and the cylinders must be of a high degree of friction, and, since this is a wheel drive, it rotates at a relatively low speed. Further, since the inner ends of the cylinders move translatory on an inner ring, there is not only a reciprocal movement between the pistons and the cylinders but also the pistons oscillate within the cylinders. This oscillatory movement, while satisfactory for low speed wheel drives, it not felt to be satisfactory for high speed operation not only because of the difficulty of sealing the oscillatory movement, but also because of the higher inherent friction therein and also the high friction inherent in the previously described engagement of the positioning rings and the cylinders.
The present invention does away with the unitary positioning ring for all the cylinders and also does away with the oscillatory movement between the pistons and the cylinders so that a low friction engine is accomplished, which engine can be satisfactorily operated at high speeds if desired, while also being suitable for low speed operation.
The following is a list of U.S. patents in the general field of this invention in that they have radially disposed pistons, but, since they do not have reciprocating cylinders, are not deemed relevant to the present invention as claimed: U.S. Pat. Nos. 3,492,948; 3,577,830; 3,744,380; and 3,924,968.